Diagnostic kits for use in screening individuals for infection with human immunodeficiency virus (HIV) infection frequently include reagents comprising HIV antigens which are used to detect antibodies using known immunological techniques including ELISA, Western Blot, latex agglutination and immuno-luminescent and immuno-fluorescent techniques.
The effectiveness of such techniques however depends upon selection of suitable immunological reagents and one particular difficulty which arises is that particular reagents are often specific to individual strains or groups of strains of HIV. Thus, for example, known diagnostic reagents based upon HIV-1 may fail to detect antibodies resulting from an infection of a patient with HIV-2.
Similarly, in the production of vaccines designed to protect individuals against HIV infection, the use of antigens derived from one particular strain of HIV may fail to provide adeguate protection against infection with other strains.
Synthesis and cleavage of the HIV-I pol precursor polyprotein is disclosed in "Processing Protease and Reverse Transcriptase from Human Immunodeficiency Virus Type I Polyprotein in Escherichia coli" by Jan Mous et. al., Journal of Virology, Apr. 1988, p. 1433-1436. The process disclosed in this reference results in the formation of a 92 kDa polypeptide consisting of protease (18 kDa), reverse transcriptase (64 kDa) and an amino-terminal portion of endonuclease (integrase) (10 kDa). The polyprotein is thus lacking the intact endonuclease sequence (25 kDa), and thus lacks substantial antigenic epitopes representing the endonuclease (integrase). Thus, the protein is unlikely to be suited for the preparation of diagnostic tests and vaccines for HIV-I.
It is an object of the present invention to overcome such problems.